Protective cover for a disc brake and a disc brake including such a protective cover

ABSTRACT

A protective cover unit including a main cover for partly covering an aperture for access to brake linings which is accommodated in a disc brake yoke for a disc brake. The main cover includes fastenings to a U-bolt-shaped lining holder which is connected to the brake yoke and runs transversely across the aperture. The main cover abuts against a portion of the brake yoke outer surface which at least partly surrounds the aperture.

TECHNICAL FIELD

The present invention relates to a protective cover unit for a discbrake according to the preamble of claim 1 and a disc brake unitincluding such a protective cover unit.

STATE OF THE ART

Disc brakes for road vehicles, and particularly for heavy utilityvehicles, suffer from considerable problems due to fouling of disc brakeunits by dust, water and waterborne pollutants which contaminate, whenthe vehicle is in motion, both disc brakes and brake yokes with brakelinings. This can have consequences in terms of effects on moving parts.Dirt and corrosion may in particular lead to functional impairmentcausing uneven or impaired braking effect as between different discbrake units.

Moreover, differences in braking action and consequently uneven wear ofbrake linings may occur on the different sides of a disc if the liningsare contaminated to different extents. All in all, in the state of theart, these problems reduce the usability of disc brakes and shortenservice intervals, thereby increasing costs. This situation has also ledto otherwise less efficient drum brakes being regarded as more reliableand as requiring less servicing.

Various attempts at alleviating the problems of disc brakes haveresulted in shaft-mounted protection surrounding the brake disc, butthis has entailed problems of impaired cooling, inherent oscillationsand extra unsprung weight.

Brake yokes for disc brakes normally have an aperture for the extractionand insertion of brake linings and for inspection of the interior of thebrake yoke. With a view to protecting the brake yoke's constituent partsand the brake disc against contamination via this aperture, it has beenproposed to insert a protective plate which is integral with the liningholder. However, that solution has not entirely solved the problems ofcontamination via the extraction aperture, and such a protective plateis troublesome to fit and remove and has therefore hinderedaccessibility. The position of the protective plate within the apertureclose to the brake linings is also regarded as hindering air flow andthereby reducing cooling.

OBJECTS AND MOST IMPORTANT CHARACTERISTICS OF THE INVENTION

One object of the present invention is to indicate a protective coverunit for a disc brake of the kind mentioned in the introduction, wherebythe problems of the state of the art are reduced. A particular object isto propose a protective cover unit which functions better and iseconomic to manufacture and fit.

These objects are achieved in the case of a protective cover unit of thekind mentioned in the introduction by the features in the characterisingpart of claim 1.

The result is a functional solution which is easy to fit to and removefrom the lining holder. The fact that it abuts against an outer surfaceof the brake yoke prevents the formation of dust accumulation pocketswhich might entail risk of dirt being led into the aperture.

It should be noted that the space outside the brake yoke is very limitedbecause of proximity to a wheel rim in cases where the brake unit isfitted adjacent to a wheel. However, a main cover according to theinvention may, through its connection to the brake yoke, be made so thinand yet stable as not only to perform properly its protective functionbut also to be clear of a rotating wheel rim.

The invention results in reduced contamination in the region of thebrake yoke and hence a more even braking action and more even liningwear, with the overall effects of greater functional reliability andlonger service intervals for the brake disc units here concerned.

The main cover preferably provides protection for indicating cables frombrake linings. In this respect it is of great advantage if the maincover is provided with lateral tabs which press these cables inwardstowards the brake yoke, i.e. away from the region of a rotating wheelrim which might otherwise damage these cables.

In the case of a single-mounted wheel it is advantageous that the maincover be supplemented by an outer cover which reduces dirt ingress viathe slits in the main cover.

Further advantages arise from further aspects of the invention which areindicated by the following detailed description of embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The attached drawings are as follows:

FIG. 1 depicts schematically a section through a vehicle wheel with adisc brake unit according to the invention,

FIG. 2 depicts parts of the disc brake unit in FIG. 1 in a partlydismantled perspective view,

FIG. 3 depicts a partly dismantled perspective view of an alternativeembodiment of a disc brake unit according to the invention,

FIG. 4 depicts a plan view of a main cover,

FIG. 5 depicts a side view of the main cover in FIG. 4 and

FIG. 6 depicts a plan view of an outer cover.

DESCRIPTION OF EMBODIMENTS

FIG. 1 thus depicts in section a vehicle wheel with a disc brake unit 1placed within the circumference of a wheel rim 3 which supports avehicle tyre 2. Broken lines at 4 represent a wheelshaft to which thevehicle wheel is fastened.

The disc brake unit 1 comprises a brake yoke 5, a brake disc 6 fastenedto the wheelshaft 4, and brake linings 7 which are arranged on brakeblocks and are for braking cooperation with the brake disc 6. The brakeyoke 5 comprises brake supports 8 (one depicted) for firm mounting ofthe brake yoke 5. Each brake support 8 has its lower region lengthenedso as to be designed to constitute a fastening point for a protectiveshield 9 which comprises a protective plate 10 and a fastening bracketportion 11.

A main cover 17 forming part of a protective cover unit according to theinvention is fastened to a lining holder 18 in the upper region of thebrake yoke S.

FIG. 2 depicts in perspective the brake yoke 5 with its brake supports8, 8′, each of which is provided with a number of fastening holes 15(shown in the brake support 8′) for accommodating fastening bolts forthe brake yoke 5. Ref. B denotes a brake disc

The outer extremity of the free end of each brake support 8, 8′ isprovided with a fastening eye 13, 13′ with respective fastening holes14, 14′ for fastening screws 12, 12′ intended to secure a unitcomprising the protective plate 10 and fastening brackets 11, 11′ bycooperation with holes provided in the free end portions of thefastening brackets 11, 11′. The fastening brackets 11, 11′ have a flatU-shaped cross-sectional profile and are curved so that they togethersubstantially describe a circular arc which is at a substantiallyradially even distance from a wheelshaft when the brake shield is inposition.

The contact surface between the protective plate 10 and the fasteningbrackets 11, 11′ is substantially planar.

The radially innermost portion of the protective plate 10 is situated ata distance from the wheelshaft (ref. 4 in FIG. 1) such that a coolingair flow can pass through the resulting gap and proceed radially alongthe brake disc. The radially outer periphery of the protective plate 10is drawn somewhat inwards towards the brake disc so as to create asomewhat enclosing structure.

The brake yoke 5 has in its upper portion an open recess 16 via whichbrake linings are intended to be extracted when they are being changed.The recess 16 is also used for other service operations relating to thedisc brake unit, and for inspection purposes.

A lining holder 18 in the form of a supporting U-bolt is placedtransversely across the recess so as to extend substantially parallelwith the wheelshaft. According to the invention, this lining holder 18is used for fixing a main cover 17 which is intended to provide dirtprotection preventing the ingress of pollutants into the recess 16. Tothis end, the main cover 17 substantially covers the adjacent outerarcuate section of the brake yoke.

The main cover comprises a thin sheetmetal structure designed to coversaid recess. The fastening of the main cover is by fastening cooperationwith the lining holder 18 whereby fastening screws 20 are inserted incountersunk recesses 19 with holes running through the main cover 17 andare screwed firmly into the lining holder 18.

The main cover 17 is also provided with tabs 34 intended to cooperatewith and protect indicating cables (see FIG. 5) for indicating the stateof wear of the brake linings. These cables take the form of wiringrouted from the respective brake linings to the vehicle's controlsystem. This involves a cable from one of the brake linings being routedthrough a duct in the upper inner region 45 (FIG. 2) of the liningholder and being thus protected from external effects of the main cover17.

A multiplicity of ventilation slits 33 are arranged in the main cover toallow flow of air which has been used for cooling and which emanatesfrom the region of the disc brake during operation of the vehicle.Cooling of the brake unit is thus promoted despite the presence of themain cover.

FIG. 3 depicts another embodiment of the invention whereby fasteningregions 23 distributed along the peripheral region of the protectiveplate 10 are used for fastening a protective housing 22. The lattercomprises a first portion 24 which runs substantially parallel with theprotective plate 10, and a second portion 25 which runs, in a mannersurrounding the brake disc, substantially at right angles to the firstportion 24 and the protective plate 10. A structure enclosing both sidesand the circumference of the brake disc is thus formed.

The fastening regions 23 are matched by corresponding portions of theprotective housing 22, and joining together is done, for example, byspot welding or by upset riveting.

Adding the protective housing 22 is applicable in the case of asingle-mounted wheel, which means that the brake disc is protected fromcontamination in all directions, which is otherwise protected by the rimof a vehicle wheel.

In its upper region directed towards the brake yoke 5, the protectivehousing 22, as also the protective plate 10, is adapted to connectingclosely adjacent portions of the brake yoke 5 while leaving a gap forflow of cooling air towards an adjacent wheelshaft (not depicted).

At its upper portion, the brake disc unit in the case of asingle-mounted wheel is supplemented by fitting an additional outercover 26 outside the main cover 17. This outer cover 26 is preferably ata substantially even distance from the main cover 17 so as to leave anair gap 27 between the main cover 17 and the outer cover 26. To thisend, the outer cover 26 has a number of spacing portions 35 which helpto maintain the continuity of the air gap 27. The spacing portions 35also serve as regions for joining together the main cover and the outercover, e.g. by upset riveting.

The object of the outer cover 26 is to protect the disc brake unit 1from ingress of dirt, water etc. via the slits 33 in the main cover 17(see FIG. 2). The fastening of the outer cover 26 to a main cover isadvantageously effected by the same fastening screws as for the maincover 17 as individual parts of the lining holder 18. Advantageously,both the main cover 17 and the outer cover 26 are manufactured aspressed sheetmetal parts.

FIG. 4 depicts the main cover 17 in a plan view in which the hatchedregions 36 represent the areas where the main cover 17 abutsoverlappingly against part of the arcuate, preferably cylindrical, outersurface of the brake yoke, which outer surface partly surrounds theaperture (ref. 16 in FIG. 2). Ref. 38 denotes a turned-down sidewall.Reinforcing grooves 39 and 40 are pressed into the main cover and runcircumferentially relative to the disc brake unit.

FIG. 5 shows the function of the lateral tabs 34. The routing of anindicating cable 41 from a brake lining is controlled by an inwardpressure imparted to it by the lateral tab 34. The cable is thusprevented from moving radially outwards to the region of a rotatingwheel rim (represented by ref. 42) which might otherwise damage thecable.

FIG. 6 depicts the outer cover 26 with holes 44 running through it forfitting fastening screws into the main cover. Spacing and joiningportions 35 are designed to cooperate with corresponding pressings 37 inthe main cover (see FIG. 4) and to be used for joining these partstogether, e.g. by upset riveting. A curved reinforcing groove 43 ispressed in the material.

The invention may be modified within the scopes of the ensuing claimswhereby the constituent parts may be configured otherwise, e.g. so thatthere is greater or smaller overlapping of surfaces. The pressings maybe configured otherwise, as also the provision of holes.

It is preferable that the protective shield and the protective coverunit be used in combination, but it is not excluded that either may beused without the other.

Applying the invention to a disc brake results in significantimprovements as regards service life and function. It also results inmore even brake lining wear and consequently longer service intervalsbetween brake lining changes.

1. A protective cover unit for at least partly covering an aperture foraccess to brake linings and which is accommodated in a disc brake yokefor a disc brake, comprising: a main cover including fasteners forfastening to a U-bolt-shaped lining holder which is connected to thebrake yoke and which runs transversely across the aperture, and the maincover is shaped to abut against a portion of the brake yoke outersurface which at least partly surrounds the aperture.
 2. (canceled)
 3. Aprotective cover unit according to claim 1, wherein the main coverincludes a multiplicity of slits for flow of air which cools the discbrake.
 4. A protective cover unit according to claim 1, wherein the maincover includes countersunk recesses which are provided with holes toserve as seats for threaded connections running through the holes.
 5. Aprotective cover unit according to claim 1, further comprising at leastone indicating cable for brake lining wear indication for which the maincover provides protection.
 6. A protective cover unit according to claim5, wherein the main cover in a selected position on the brake yoke hasat least one lateral tab bent inward towards the disc brake centerlinefor abutment against the indicating cable.
 7. A protective cover unitaccording to claim 1, further comprising an outer cover fastened to themain cover, the covers being so shaped and fastened as to form betweenthem a substantially even air gap.
 8. A protective cover unit accordingto claim 7, wherein the main cover and the outer cover each comprise apressed sheet metal part.
 9. A protective cover unit according to claim8, wherein at least one of the main cover and the outer cover haspressed into it at least one of a spacing means, a reinforcing groove,and a joining surface.
 10. A protective cover unit according to claim 7,further comprising upset riveting uniting the outer cover and the innercover.
 11. A disc brake unit including brake linings; a brake yoke for adisc brake; a U-shaped lining holder which is connected to the brakeyoke; an aperture in the brake yoke for access to the brake linings atthe yoke; a protective cover unit for at least partly covering theaperture and blocking access to the brake linings and which isaccommodated in the disc brake yoke, the cover unit comprising: a maincover including fasteners for fastening the main cover to the liningholder, and the cover runs transversely across the aperture, and themain cover is shaped to abut against a portion of the brake yoke outersurface which at least partly surrounds the aperture.
 12. A disc brakeunit according to claim 11, wherein the portion has substantiallyarcuate geometry.
 13. A disc brake unit according to claim 12, whereinthe main cover includes a multiplicity of slits for flow of air whichcools the disc brake.
 14. A disc brake unit according to claim 12,wherein the main cover includes countersunk recesses which are providedwith holes to serve as seats for threaded connections running throughthe holes.
 15. A disc brake unit according to claim 12, furthercomprising at least one indicating cable for brake lining wearindication for which the main cover provides protection.
 16. A discbrake unit according to claim 12, wherein the main cover in a selectedposition on the brake yoke has at least one lateral tab bent inwardtowards the disc brake centerline for abutment against the indicatingcable.
 17. A disk brake unit according to claim 12, further comprisingan outer cover fastened to the main cover, the covers being so shapedand fastened as to with the form between them a substantially even airgap.
 18. A disk brake unit according to claim 17, wherein the main coverand the outer cover each comprise a pressed sheet metal part.
 19. A diskbrake unit according to claim 18, wherein at least one of the main coverand the outer cover has pressed into it at least one of a spacing means,a reinforcing groove, and a joining surface.
 20. A disk brake unitaccording to claim 17, further comprising upset riveting uniting theouter cover and the inner cover.